Analyzing receiver



April 26, 1949- L. F. JAGGI, JR., Er'l. l2,468,073

ANALYZ ING RECEIVER I 2 sheets-sheet 1 FiLed Jan. 23, 1945 Le wus F. Mcm Jn ANDREW DSHEARER (Se no M.wn |AMs v @ZAM Y im HTTOR/VEV April 26, 1949- L. F. JAGGI, JR., Er AL 2,463,073

ANALYZING RECEIVER Filed Jan. 23, 1945 2 sheets-sheet 2 AN 2 I...

INVENTOR. LEWlS EJAGGIJR.

ANDREW D.SHEARER BY EVER/m MWILLIAMS 197' TORNE Patented Apr. 26, 1949 AN ALYZING RECEIVER Lewis F. J aggi, Jr., Everard M. Williams, and Andrew D. Shearer, Dayton, Ohio Application January 23, 1945, Serial No. 574,162

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 4 Claims.y

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

The invention relates to radio analyzing receivers and more particularly to a means and method for detecting the frequency of a radio signal and tuning in on the signal.

.The objects of the present invention include the provision of a means and a method for locating one or a plurality of rapidly alterable radio signals, tuning in on a given signal and listening to its message or jamming the signal with a minimum of apparatus.

An embodiment of the present invention is shown in diagram and block form in the accompanying drawings wherein:

Fig. 1 is a block diagram of a panoramic receiver, a radiating receiver and a visual presentation means that in combination provide a device for practicing the present invention;

Fig 2 is a View of two pips that illustrate two intercepted signals as they appear upon the oscilloscope screen that forms a part of the device that is illustrated in Fig. 1;

Fig. 3 is an oscilloscope screen View showing the method of tuning the radiating receiver by means of visual coincidence between a pip representing an intercepted signal and a pip representing the frequency to which the receiver is tuned; and

Fig, 4 is an oscillocope screen View of the signal from the radiating receiver superimposed upon one of the intercepted signals.

The apparatus that is used in following the method that forms a part of the subject matter of the present invention comprises a wide band panoramic receiver I that has as parts thereof a continuously variable tuning capacitor having one set of rotatable plates 2 that are mounted upon a shaft 3 of a motor 4 and that are rotated thereby through sets of capacitor fixed plates 5 and 5a that are immovably mounted upon a base that preferably also supports the other parts of the wide band panoramic receiver I. The condenser xed plates 5 and 5a have an inductor B connected therebetween as shown, and coupled with a grounded inductor 1 in series with an antenna 8. A iiy wheel 9 assists in damping out irregularities in the mechanical motion of the motor shaft 3 upon which it is mounted. The rotation of thecapacitor plates 2 Withrespect to the tixed capacitor plates 5 and 5a and the inductor i tune the receiver I to a wide band. The radio frequency part of the assembly, of which the tuned capacitor forms a part, feeds into a video amplifier I9 thru a demodulator 20. The video amplifier I9 and sweep circuit 2|, are Wired to a pair of posts of a double pole double throw switch I I. An audio amplifier 29 in a radiating receiver 2 33 and sweep generator I0 are wired to another pair of posts of the switch II. The switch II has its fixed posts bridging a cathode ray tube I2, as shown, The return circuits may be thru ground, not shown.

A circular disc I3 is mounted upon the motor shaft 3 with its plane substantially normal to the axis of the shaft 3i The disc I3 has an opening extending therethru, such as an aperture Id, or the like. A light source I5 is disposed upon one side of the aperture I4 in the disc I3 and an aligned photo-electric tube l5 is disposed upon the opposite side of the aperture in the disc i3. The tube IG is blacked out over enough of its circumference to provide a narrow window I7 in the side thereof that is adjacent to the aperture I4 in the disc I3. With each revolution of the disc I3, an instantaneous light impulse from the light source I5 passes thru the disc aperture I 4 and thru the tube window Ii to cause the tube I6 to supply a voltage.

The voltage from the photo-electric tube IB iires a thyratron I3, that preferably is a part of a sweep circuit 2I. The sweep circuit 2| produces a saw-tooth output that is appliedthrough the switch II to the horizontal plates of the cathode ray tube I2, The sweep circuit 2l is interposed between the tube I6 and a contact of the switch II. The saw-tooth wave is thus synchronized wth the rotation of the tuning capacitor plates 2 by operation of the moto-r t, Any intercepted signals that are received by the antenna 8 and that are applied to the capacitor plates 2, 5y and 5a, and the inductor 6, produce vertical displacements or pips 25 and 26 in the horizontal trace 22 on the oscilloscope screen 23.

A radiating receiver 33 is also provided for supplying a controlled reference pip in the trace 22 upon the screen 23 of the cathode ray tube I2. The radiating receiver 33 preferably contains a radiating detector, such as a superregenerative detector 21, or may employ a detector whose in.. ductance-capacitance circuit is switched to an oscillator tube or other suitable radio energy emitting device. The energy which this detector or device radiates is ci the same frequency as that to which the radiating receiver 33 is tuned for reception. The radiating receiver is tuned by a variable capacitor 23 or the like. The capacitor 28 is controlled by a knob, not shown, that is calibrated to frequency. The detector 21 is connected in series thru an audio amplifier 29, that is connected to a post of the switch II, to an audible device, such as head phones 3E) or the like. The detector 2l receives signals from its antenna 3 I The arm of the switch II is adapted to conneet releasably the cathode ray tube I2 to the sweep circuit 2l and the video amplifier I9 for purposes of signal presentation. The arm of the 3 switch l I is also adapted to connect releasably the cathode ray tube I2 to the sweep generator I0 and the audio amplifier 29 for observing the effect of an intercepted signal.

Signals may be intercepted by the wide band panoramic receiver I and tuned in at their respective frequencies. When the arm of the switch I I is thrown toward the left, the cathode ray tube I2 is connected to the panoramic receiver I, and the intercepted signals appear as pips, such as 25 and 26, that extend upwardly from the base line 22 upon the oscilloscope screen 23. The radiating receiver 33 is tuned to any one of the signays by visually obtaining a coincidence between the pip representing the intercepted signal and the pip representing the radiating receiver tuning with the switch I I thrown toward the left so that the frequency of the intercepted signal may be determined.

The operation of the variable capacitor 28 permits the pip 32 from the radiating detector 21 to be moved laterally along the trace 22 until it is superimposed upon or brought substantially into registration with the pip 25 from the intercepted signal as shown in Fig. 4 of the drawing. When the two pips are matched, the same intercepted signal is being received in the listening detector that is being observed in the cathode ray tube. When the two pips are matched or so positioned, the frequency in megacycles of the intercepted signal that appears upon the oscilloscope screen 23 as the intercepted pip 25 may be read from the frequency scale of the variable capacitor 28. With the signals so matched, the switch I I is thrown to the right to place the cathode ray tube I2 in connection with the variable sweep generator I and the audio amplifier 29. When so connected the modulation envelope of the intercepted signal is placed upon rthe oscilloscope screen 23 for analysis. Thus, any one of the signals intercepted by the panoramic receiver may be simultaneously observed visually and listened to by the operator of the device or the information so obtained may be used in any other desired manner. The same procedure may be followed for calibrating a panoramic receiver by the use of energy that is radiated from a calibrated detector.

It will be understood that the particular assembly of instruments and mechanical details that have been disclosed herein have been submitted for the purposes of illustrating and describing the present invention and that various wiring modifications and similarly functioning instruments, devices and parts thereof may be substituted therefor without departing from the present invention as defined by the claims that are appended hereto.

We claim: f

1. A radio signal analyzing receiver comprising in combination, a radio receiver having a panoramic sweep, a tunable radio receiver, a radiating detector part of said tunable radio receiver capable of radiating radio energy of substantially the same frequency as that to which it is tuned for reception, a cathode ray tube oscilloscope, a sweep generator independent of said panoramic receiver sweep, a switch means for alternately connecting said oscilloscope with said first radio receiver to provide a panoramic receiver and with said sweep generator and said tunable radio receiver to provide' a signal analyzer, and means whereby the tuning of said tunable receiver is indicated visually upon said oscilloscope.

2. In combination a panoramic receiver having means for continuously and cyclically tuning it over a band of frequencies, a first indicating means for simultaneously providing separate indications of signals of different frequencies received in said band, a radiating receiver having adjustable, calibrated tuning means to tune it for reception of any one signal frequency within said band, the frequency of the signal radiated by said radiating receiver being equal to the frequency to which it is tuned for reception, means to impress the radiated signal upon said first receiver so that it is indicated upon said indicating means together with all other indicated signals, whereby, when said radiating receiver is adjusted to receive a signal of a given frequency, the indication of the signal radiated by said receiver registers with one of the received signals and the frequency of the latter is indicated by said calibrated tuning means, and a second visual indicating means receptive of the output of said radiating receiver for translating the modulation characteristics of the signal to which said radiating receiver is tuned.

3. The combination set forth in claim 2, wherein both of said indicating means comprise a common cathode ray oscilloscope.

4. In combination a panoramic receiver having means for continuously and cyclically tuning it over a band of frequencies, a first means includingan indicating means for simultaneously providing separate indications of signals of different frequencies received in said band, a radiating receiver having adjustable, calibrated tuning means to tune it for reception of any one signal frequency within said band, the frequency of the signal radiatedby said radiating receiver being equal to the frequency to which it is tuned for reception, means to impress the radiated signal upon said first receiver so that it is indicated upon said indicating means together with all other indicated signals, whereby, when said radiating receiver is adjusted to receive a signal of a given frequency, the indication of the signal radiated by said receiver registers with one of the received signals and the frequency of the latter is indicated by said calibrated tuning means, and a second means including said indicating means receptive of the' output of said radiating receiver for displaying the modulation envelope of the signal to which said radiating receiver is tuned.

- LEWIS F. JAGGI, JR.

EVERARD M. WILLIAMS. ANDREW D. SHEARER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,455,768 Slepian May 15, 1923 1,687,933 Farrington Oct. 16, 1928 2,159,790 Freystedt et al. May 23, 1939 2,312,203 Wallace Feb. 23, 1943 2,363,583 Gilman Nov. 28, 1944 2,367,907 Wallace Jan. 23, 1945 2,378,604 Wallace June 19, 1945 2,418,139 Preisman Apr. 1, 1947 FOREIGN PATENTS Number Country Date 113,637 Australia Aug. 21, 1941 OTHER REFERENCES Radio, Panoramic Radio Reception by Popkin-Clurman, March 1942, pp. 15 to 18 and 46 to 49. Z50-20.41F. 

